MR.  J.  O.  WESTWOOD  ON  NYCTERIBIA. 
285 
and  rounded.  Montagu,  however,  who  describes  the  abdomen  of  the  styliferous  spe- 
cimens of  the  species  from  which  Dr.  Leach  derived  his  characters  as  being  apparently 
composed  of  three  divisions,  states  that  in  another  specimen  the  abdomen  appeared  four- 
jointed,  more  ovate,  tumid,  and  destitute  of  posterior  appendages ;  this  he  regarded  as 
a  female,  and  the  former  as  a  male.  From  my  subsequent  observations  it  will  be  seen 
that  the  supposition  of  Dr.  Leach  w^as  the  correct  one.  Latreille  also  differs  in  opinion 
from  Dr.  Leach,  considering  the  styhferous  individuals  as  males,  and  those  with  a 
greater  number  of  articulations,  and  without  exserted  terminal  appendages,  as  females  ; 
and  he  consequently  describes  the  abdomen  of  the  supposed  female  of  his  misnamed 
Nyct.  Blainvillii  as  ovoid,  six -jointed,  the  last  joint  being  elongate-conic,  narrowed  to 
the  tip,  and  truncate  ;  but  as  he  has  not  mentioned  the  existence  or  nonexistence  of 
inflected  styles  or  other  male  apparatus,  a  shght  degree  of  doubt  must  remain  as  to 
the  sex  of  his  insect,  notwithstanding  that  its  six-jointed  abdomen  would  induce  us  to 
suppose,  with  reference  to  the  characters  of  Colonel  Sykes's  insect,  that  it  must  be  a 
male ;  as,  indeed,  M.  Dufour  has  presumed. 
The  last-named  author  '  has  described  the  abdomen  of  two  kinds  of  individuals  of  his 
Nycte'ribie  de  la  Chauve-Souris,  that  of  the  female  being  cylindric-oval,  apparently 
destitute  of  articulations,  furnished  on  its  upper  surface  with  three  pairs  of  pectiniform 
series  of  short  hairs  varying  in  their  direction,  and  setose  at  its  extremity :  that  of 
the  male  is  smaller,  oblong,  and  exhibits  on  the  upper  side  six  distinct  segments,  of 
which  the  last  is  slightly  attenuated  and  truncate  at  the  tip.  He  adds,  "  L'exploration 
la  plus  attentive  de  I'extremite  de  I'abdomen  ne  m'a  fait  decouvrir  a  celle-ci  aucun 
appendice,  aucun  stylet,  aucune  sole  particuli^re."  He  regrets,  however,  that  he  did 
not  endeavour,  by  compression,  to  discover  if  these  organs  were  not  retracted.  That 
the  former  of  these  descriptions  is  taken  from  a  female  insect  is  not  to  be  doubted  ;  and 
the  other  description  is  so  different  as  to  induce  us  to  believe  that  it  is  taken  from  a 
male,  notwithstanding  the  want  of  any  visible  male  organs  :  these,  however,  as  we  shall 
subsequently  see,  are  occasionally  not  prominent,  but  laid  closely  along  the  under  sur- 
face of  the  abdomen.  And  I  am  so  confident  that  this  would  be  the  casein  the  real  males 
of  M.  Dufour's  insect,  that,  should  this  author  be  perfectly  correct  in  his  descriptions, 
and  not  have  overlooked  the  male  organs,  I  should  feel  no  hesitation  in  regarding  his 
smaller  insects,  not  as  males  having  the  mascuUne  organs  retractile  within  the  last  seg- 
ment of  the  abdomen,  (which  1  have  never  found  to  be  the  case,)  but  as  females  of  the 
same  or  even  of  a  different  species,  and  most  probably  in  an  unimpregnated  state  ;  con- 
ceiving that  gestation  and  subsequent  parturition  would  materially  alter  the  character 
of  this  part  of  the  body. 
'  It  should  be  obsen^ed  that  this  author  has  misstated  Dr.  Leach's  opinion  in  his  observation,  "  Suivant 
M.  Leach  ce  sont  les  individus  qui  ont  moins  de  segmens  a  I'abdomen  qui  sent  les  males."  He  has  eWdently 
mistaken  Latreille's  conclusions  upon  this  point,  in  the  '  Dictipnnaire  d'Histoire  Naturelle,'  for  the  opinion  of 
Dr.  Leach. 
2  P  2 
